Cooling apparatus and electronic apparatus

ABSTRACT

The cooling apparatus includes a heat receiving portion to receive heat from the heating element, a radiator, a first heat pipe having one end portion to receive heat from the heat receiving portion and anther end portion inserted in the radiator, and a second heat pipe to receive the heat from the heat receiving portion via the first heat pipe, the second heat pipe including one end portion arranged on the first pipe and another end portion arranged around the radiator, wherein the second heat pipe overlaps with a region of the first heat pipe extending from the heat receiving portion to the radiator in a plan view of the cooling apparatus.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2010-293111, filed on Dec. 28,2010, the entire contents of which are incorporated herein by reference.

FIELD

This invention relates to a cooling apparatus (cooling device), and anelectronic apparatus having a cooling apparatus.

BACKGROUND

Recently, in the field of electronic apparatus such as a personalcomputer (hereafter, abbreviated as PC), sophistication of componentsconstituting the electronic apparatus such as CPU (Central ProcessingUnit), VGA (Video Graphics Accelerator) or other graphic chip, HDD (HardDisk Drive) and VRAM (Video Random Access Memory) has created a tendencyto increase an amount of heat generated in the electronic apparatus.

In particular, portable so-called laptop PCs and tablet PCs have beenmade smaller, thinner, and lighter, so that the convenience is improvedespecially in terms of portability. As a result, the density of heatgenerating components mounted on a substrate or the like is increasedmore and more. In order to deal with such increase of heat density,various heat sinks serving as cooling apparatuses have been proposed toimprove the efficiency of heat dissipation (see, for example, JapanesePatent Application Laid-open No. 2004-150719).

SUMMARY

An aspect of the invention relates to a cooling apparatus for cooling aheating element accommodated in electronic apparatus. The coolingapparatus includes a heat receiving portion to receive heat from theheating element, a radiator, a first heat pipe having one end portion toreceive heat from the heat receiving portion and anther end portioninserted in the radiator, and a second heat pipe to receive the heatfrom the heat receiving portion via the first heat pipe, the second heatpipe including one end portion arranged on the first pipe and anotherend portion arranged around the radiator, wherein the second heat pipeoverlaps with a region of the first heat pipe extending from the heatreceiving portion to the radiator in a plan view of the coolingapparatus.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating by way of example a coolingapparatus according to a first embodiment;

FIG. 2 is a perspective view illustrating by way of example anothercooling apparatus according to the first embodiment;

FIG. 3 is a schematic cross-sectional view obtained by cutting thecooling apparatus illustrated in FIG. 2 along the A-A line;

FIG. 4 is a perspective view of the cooling apparatus illustrated inFIG. 2, as viewed from the outside of the curve of a heat pipe;

FIG. 5 is a schematic cross-sectional view obtained by cutting thecooling apparatus illustrated in FIG. 2 along the B-B line;

FIG. 6 is a perspective view illustrating a modification example of thecooling apparatus illustrated in FIG. 1;

FIG. 7 is a perspective view illustrating another modification exampleof the cooling apparatus illustrated in FIG. 1;

FIG. 8 is a perspective view illustrating by way of example a coolingapparatus according to a second embodiment;

FIG. 9 is a perspective view illustrating, by way of example, anothercooling apparatus according to the second embodiment; and

FIG. 10 is a perspective view illustrating a modification example of acooling apparatus according to a third embodiment.

FIG. 11 is a perspective view illustrating a modification example of thecooling apparatus according to the third embodiment;

FIG. 12 is a perspective view illustrating by way of example a coolingapparatus according to a fourth embodiment of the invention;

FIG. 13 is an overall perspective view of electronic apparatus;

FIG. 14 is an exploded view of the electronic apparatus as viewed fromabove;

FIG. 15 is an exploded view of the electronic apparatus;

FIG. 16 is an exploded view of the electronic apparatus as view frombelow;

FIG. 17A and FIG. 17B are diagrams for explaining a fan mechanism and acooling apparatus mounted in electronic apparatus; and

FIG. 18 is a schematic perspective view illustrating, as a comparisonexample, a cooling apparatus employing a forced air cooling system.

DESCRIPTION OF EMBODIMENTS

Referring to the drawings, exemplary preferred embodiments of theinvention will be described. However, configurations of the embodimentsdescribed below are provided by way of example only, and the inventionis not limited to constructions or configurations of these embodiments.Before describing the embodiments of the invention, a cooling apparatusas a comparison example will be described.

Comparison Example

FIG. 18 is a schematic perspective view illustrating, as a comparisonexample, a cooling apparatus employing a small-sized fan (notillustrated). This cooling apparatus corresponds to a forced air coolingsystem. A cooling apparatus 20 illustrated in FIG. 18 is configured tocool two heating elements by transporting heat generated by theseheating elements to a radiator which dissipates the heat. The coolingapparatus 20 is composed of bases 23 and 25 each having a heat receivingportion, heat pipes 21 and 22, and a radiator 24, and these componentsare thermally connected. Heat from the heating elements is transportedto the heat pipes 21 and 22 via the heat receiving portions 23 and 25provided in the bases. The heat conducted to the heat receiving portionof the base 23 is further conducted to one end of the heat pipe 21 whichis bent, and is transported to the radiator 24 into which the other endof the heat pipe 21 is inserted. The heat transferred to the heatreceiving portion of the base 25 is transferred to one end of the heatpipe 22 which is bent, and transported to the radiator 24 into which theother end of the heat pipe 22 is inserted. The radiator 24 has aplurality of heat dissipation fins 24 a thermally connected to the heatpipes 21 and 22. The heat dissipation fins 24 a are arranged in a row atpredetermined intervals according to an amount of heat to be dissipated.The radiator 24 dissipates the heat transported from the heat generatingcomponents through the heat pipes 21 and 22 by receiving forced coolingair from a small-sized fan (not illustrated).

However, the cooling apparatus 20 illustrated in FIG. 18, which employsa configuration in which the entire of the heat pipes 21 and 22 arearranged side by side in a planar direction, occupies a significant areain the planar direction within the electronic apparatus. Particularly,the cooling apparatus 20 employs a configuration in which the other endsof the heat pipes 21 and 22 are arranged in the inside of the radiator(heat dissipation fins) 24 such that they lie side by side in a planardirection. Therefore, the radiator 24 becomes greater in size than aradiator configured such that a single heat pipe is inserted therein,which hinders effective use of the limited space available within theelectronic apparatus. Furthermore, the insertion of the two heat pipes21 and 22 into the radiator 24 causes a problem that the heat pipe 21cannot receive sufficient air from the fan (not illustrated), resultingin impediment to proper heat dissipation.

As described above, the radiator 24 is prepared as a different type ofradiator from a radiator in which a single pipe is inserted. However, itwill be desirable if a common radiator can be used regardless of howmany heat pipes are inserted therein, because cost reduction may berealized by decreasing the number of radiators to be managed. Further,if the size of the radiator remains unchanged regardless of the numberof heat pipes, it will contribute to improve the degree of freedom inlayout of various parts and components in electronic apparatus.

<<Cooling Apparatus>>

First Embodiment

FIG. 1 is a perspective view illustrating by way of example a coolingapparatus 10 according to a first embodiment. The cooling apparatus 10illustrated in FIG. 1 is a cooling apparatus for cooling a heatgenerating component (also referred to as “heating element”) such as CPUor other electronic circuit chip mounted on a motherboard, a substrateor the like provided in electronic apparatus 30 (FIG. 13). As describedlater, the cooling apparatus 10 illustrated here is of a basic form tobe combined with other cooling components (e.g. heat pipes).

As illustrated in FIG. 1 by way of example, the cooling apparatus 10 hasa base 3 having a heat receiving portion 3 a, a heat pipe 1, and aradiator (heat sink) 4. The base 3, the heat pipe 1, and the radiator 4are formed integrally. The heat pipe 1 is a flat strip-shaped heat pipefor transporting heat conducted from the heat generating component. Theheat pipe 1 is bent in a substantially L-shape. One end of the heat pipe1 is joined to the heat receiving portion 3 a of the base 3 bysoldering, for example, and is thermally connected to the heat receivingportion 3 a. The heat receiving portion 3 a is thermally connected to aheat generating component (not illustrated, also referred to as “heatingelement”) which is arranged on the lower side of the heat receivingportion 3 a as viewed in FIG. 1.

The other end of the heat pipe 1 is inserted in the radiator 4 for heatdissipation and attached thereto to be integral with the radiator 4,whereby the heat transmitted from the heating element to the heatreceiving portion 3 a is transported to the radiator 4 through the heatpipe 1. The radiator 4 has a plurality of heat dissipation fins 41 andeach of the heat dissipation fins 41 is orthogonally in contact with theplanes of the heat pipe 1 (the upper and lower flat surfaces of the heatpipe as viewed in FIG. 1).

The base 3 is a plate-like metallic member, and serves as a base plateto fix the heat pipe 1 and radiator 4 formed integrally with the base 3inside the housing of the electronic apparatus. The base 3 is providedwith a plurality of (three in FIG. 1) through holes for receivingsupport members 11 therein. The support members 11 are fixed by means ofthese through holes. Each of the support members 11 functions as aprojection having a spring and projecting from the front surface (uppersurface in FIG. 1) of the base 3 and a projection projecting from therear surface (lower surface in FIG. 1) (see FIG. 4). Each of the supportmember 11 has a through hole passing through the front- and rear-sideprojections. A screw is inserted through the through hole so that thecooling apparatus 10 is fixed to the electronic apparatus by means ofthe screw. The base 3 has the heat receiving portion 3 a, which isarranged to face the heating element within the housing of theelectronic apparatus. This allows the heat from the heating element tobe transferred to the heat receiving portion.

The heat receiving portion 3 a is a rectangular plate-shaped metallicmember, and is formed integrally with the base 3. The heat receivingportion 3 a conducts heat from the heat generating component. The base 3has a substantially rectangular cutout portion 3 b matching the shape ofthe heat receiving portion 3 a, and the heat receiving portion 3 a isreceived in the cutout portion 3 b. One surface (the lower surface asviewed in FIG. 1) of the heat receiving portion 3 a is arranged to facethe heat generating component so that heat from the heat generatingcomponent is received by the heat receiving portion 3 a. The othersurface (the upper surface in FIG. 1) of the heat receiving portion 3 ais joined to one end 1 a of the heat pipe 1 by soldering. The heatreceiving portion 3 a and the heat pipe 1 may be joined together byother joining methods such as bonding with heat-conductive tape orgrease, and mechanical fastening such as caulking. The heat pipe 1receives heat from the heat generating component at its one end 1 a viathe heat receiving portion 3 a, and transports the heat to the other end1 b of the heat pipe 1. The heat transported to the other end 1 b of theheat pipe 1 is diffused within the radiator 4, and is diffused byreceiving air from a fan mechanism 39 arranged in front of the radiator4 (FIG. 14). The heat receiving portion 3 a and the base 3 may be formedintegrally as a single component. In this case, the base 3 and the heatpipe 1 are joined together by soldering or the like.

The radiator 4 is a heat sink having a substantially rectangularparallelepiped shape, and has a plurality of heat dissipation fins 41and an anti-air-leak sheet 42. The heat dissipation fins 41 are arrangedat predetermined intervals along a longitudinal direction of theradiator 4 (along the direction of the Y-axis in FIG. 1). The pluralityof heat dissipation fins 41 are arranged orthogonally to theanti-air-leak sheet 42, and one of the sides of the radiator 4 in thelongitudinal direction forms an opening 41 c for introducing air fromthe fan. This means that the radiator 4 is opened at the other sidethereof and at the lower surface as viewed in FIG. 1 (the opposite faceto the surface where the anti-air-leak sheet 42 is provided). A fanmechanism 39 (FIG. 14) is arranged on the opening 41 c side and sendsforced cooling air toward the opening 41 c. The airflow generated by thefan mechanism 39 passes between the heat dissipation fins 41 arranged ina row and through the periphery of the radiator 4 toward the otheropened side of the radiator 4 (in the direction of the X-axis). The heatfrom the heat generating component that has been transported through theheat pipe 1 is dissipated by the airflow generated by the fan mechanismvia the thermally connected heat dissipation fins 41. The heatdissipation fins 41 may be formed by plates of a metal having a highheat conductivity such as aluminum or copper, but the material of theheat dissipation fins 41 is not limited particularly.

The anti-air-leak sheet 42 improves the cooling efficiency by preventingthe air that is supplied from the fan and passes through the heatdissipation fins 41 from leaking out of the heat dissipation fins 41.The anti-air-leak sheet 42 is bonded on the heat dissipation fins 41.The anti-air-leak sheet 42 has a flat portion 42 a extending in alongitudinal direction (the Y-axis direction), and a slope portion 42 binclined in a tapered shape and connected to the flat portion 42 a. Theslope portion 42 b is formed to be located outside the curved end 1 b ofthe heat pipe 1 inserted into the radiator 4, and has a steppedstructure having a height in the direction of the Z axis. The slopeportion 42 b is formed to be located on the side (on the side to whichthe air (see arrows in FIG. 5) from the afore-mentioned fan mechanismpasses through) of the radiator 4 which is opened facing the fanmechanism.

As illustrated in FIG. 1, the slope portion 42 b is inclined upward fromthe flat portion 42 a in the direction of the Z axis. The anti-air-leaksheet 42 may be bonded also to the side of the radiator 4 where theopening 41 c is formed, such that the opening is covered with theanti-air-leak sheet 42. In order to increase the heat capacity, theanti-air-leak sheet 42 may be formed of a metallic plate and joined tothe heat dissipation fins 41. Further, instead of using theanti-air-leak sheet 42, an upper portion and/or a lower portion of eachof the heat dissipation fins 41 illustrated in FIG. 5 may be bent in thedirection along which the heat dissipation fins 41 are arranged suchthat the cross section of each fin assumes an L-shape or U-shape asviewed from the fan mechanism side. A similar air leakage preventingfunction to that of the anti-air-leak sheet 42 can be realized in thismanner.

FIG. 2 is a perspective view illustrating by way of example a coolingapparatus 10 a having a basic configuration that is the same as that ofthe cooling apparatus 10. Whereas the cooling apparatus 10 is forcooling a single heat generating component (heating element), thecooling apparatus 10 a is for cooling a plurality of heat generatingcomponents mounted on a motherboard or the like provided in theelectronic apparatus 30. These heat generating components include, forexample, electronic components or electronic chips, such as a centralprocessing unit (CPU) and a video graphics accelerator (VGA). However,the heat generating components are not limited to CPU and VGA.

The cooling apparatus 10 a illustrated by way of example in FIG. 2 has abase 3 as a first base, a base 5 as a second base, a heat pipe 1 as afirst heat pipe, a heat pipe 6 as a second heat pipe, and a radiator 4.The heat pipe 1 and the radiator 4 used in the cooling apparatus 10 aare common parts with the cooling apparatus 10 illustrated in FIG. 1.Thus, the cooling apparatus 10 a is formed by adding, to the basicconfiguration of the cooling apparatus 10, the base 5 having a heatreceiving portion 5 a and the heat pipe 6.

In FIG. 2, the heat receiving portion 3 a of the base 3 transfers heatfrom a first heating element (e.g. CPU) to the heat pipe 1. The base 5is formed integrally with the base 3 such that it is arranged on thesame plane as the base 3. The base 5 has a heat receiving portion 5 afor receiving heat from a second heating element (e.g. VGA chip) that isdifferent from the first heating element. The heat receiving portion 5 ais connected by soldering to an intermediate portion 1 c between the oneend 1 a and the other end 1 b of the heat pipe 1. Thus, heat from thesecond heating element covered with the heat receiving portion 5 a istransferred to the heat pipe 1 via the heat receiving portion 5 a.Although the base 5 in the example illustrated in FIG. 2 is a metalliccomponent formed integrally with the base 3, the base 5 may be formedseparately from the base 3. The base 5 has two cutout portions 52 a eachhaving a substantially rectangular shape matching the shape of the heatreceiving portion 5 a.

The base 5, having fastening holes for support members, is mounted onthe electronic apparatus 30 by means of the support members 11 insertedthrough these fastening holes. The heat receiving portion 5 a and thebase 5 may be formed integrally as a single component. In this case, thebase 5 and the heat pipe 1 are joined to each other by soldering or thelike.

The heat pipe 6 is a planar cooling component for transporting heatconducted from the second heat generating component. One end 6 a of theheat pipe 6 is laid on top of the heat receiving portion 5 a with theheat pipe 1 interposed therebetween and thus joined by soldering to theheat pipe 1. The joining between the heat pipe 6 and the heat pipe 1 maybe performed by any other joining method such as bonding withheat-conductive tape or grease, or mechanical fastening such ascaulking. The heat pipe 6 is shaped into a substantially L-shape havingthe same curvature as the heat pipe 1. The other end 6 b of the heatpipe 6 is placed on the anti-air-leak sheet 42 of the radiator 4.However, the other end 6 b may be bonded to the anti-air-leak sheet 42,or may be separated from the anti-air-leak sheet 42. Further, the otherend 6 b may be arranged between the anti-air-leak sheet 42 and the heatdissipation fins 41 and bonded to the heat dissipation fins 41. In thiscase, the anti-air-leak sheet 42 assumes a configuration in which theanti-air-leak sheet 42 covers the other end 6 b of the heat pipe 6 andis bonded to the heat dissipation fins 41.

The heat pipe 6 has a similar width to that of the heat pipe 1, and isarranged to extend along the same path as the heat pipe 1 from one endto the other end thereof. In other words, the heat pipe 6 is superposedon the heat pipe 1 in the X-Y plane. The heat pipe 1 can be referred toas the base pipe since it serves as a base which the heat pipe 6 is laidon and joined to.

In this manner, it is made possible, by laying the heat pipe 6 on top ofthe heat pipe 1, to allow the heat from the second heat generatingcomponent that is received by the heat pipe 1 from the heat receivingportion 5 a to be transferred to the one end 6 a of the heat pipe 6,transported to the other end 6 b of the heat pipe 6, and dissipated bythe radiator 4.

FIG. 3 is a schematic cross-sectional view obtained by cutting thecooling component 10 a illustrated in FIG. 2 along the A-A line. As isobvious from FIG. 3, the heat pipe 6 is superposed on the surface of thethin flat heat pipe 1. The heat pipe 6 is formed such that the thicknessthereof in the Z-axis direction is substantially the same as that of theheat pipe 1, and the width thereof in the Y-axis direction is smallerthan that of the heat pipe 1. However, the width of the heat pipe 6 maybe the same or slighter greater than that of the heat pipe 1.

The lower flat surface in the Z-axis direction of the heat pipe 1 isjoined by soldering to the heat receiving portion 5 a that is attachedso as to be supported by the cutout portions 52 a, and receives heatfrom a heat generating component arranged to face the heat receivingportion 5 a, via the heat receiving portion 5 a. When the heat receivingportion 5 a and the base 5 are formed integrally as a single component,the heat pipe 1 may receive the heat from the heat generating componentvia the base 5.

The lower flat surface of the heat pipe 6 is superposed on the upperflat surface in the Z-axis direction of the heat pipe 1 in contacttherewith. The upper flat surface of the heat pipe 1 and the lower flatsurface of the heat pipe 6 are thermally connected with each other bybeing joined together at their contact surface by means of solder orother bonding material having high heat conductivity. Various joiningmethods can be used to join the heat pipe 1 and the heat pipe 6, asdescribed above. The contact surface area between the heat pipe 1 andthe heat pipe 6 can be increased by joining the flat surfaces thereof,which enables proper heat transfer from the heat pipe 1 to the heat pipe6. Accordingly, the amount of heat that can be transported to theradiator 4 is increased by superposing the heat pipe 6 on the heat pipe1, in comparison with when only the heat pipe 1 is provided. Thus, theheat conducted from the heat generating components can be transportedproperly to the radiator 4.

Returning to FIG. 2, the heat pipe 6, which is superposed at the one end6 a thereof on the heat pipe 1 at a position corresponding to the heatreceiving portion 5 a, is extended to the radiator 4 along the same pathas the heat pipe 1 in the X-Y plane. The heat pipe 6 extended to theradiator 4 is arranged such that its end is in contact with theanti-air-leak sheet 42 provided in the radiator 4 having itslongitudinal direction in the Y-axis direction. Since the other end 1 bof the heat pipe 1 is inserted into the radiator 4, the heat pipe 6joined to the heat pipe 1 at the heat receiving portion 5 a is bent suchthat it is gently inclined upward in the Z-axis direction on the heattransfer path leading to the radiator 4, before the radiator 4.

FIG. 4 is a perspective view illustrating the cooling apparatus 10 a asviewed from the outside of the curve of the heat pipe 1. As illustratedin FIG. 4, the heat pipe 6 is inclined upward in the Z-axis directionbefore the radiator 4 so as to be separated from the heat pipe 1, andarranged on the radiator 4. This means that the one end 6 a of the heatpipe 6 is joined to the heat pipe 1 in contact therewith, while theother end 6 b is separated from the heat pipe 1.

FIG. 5 is a schematic cross-sectional view obtained by cutting thecooling apparatus 10 a illustrated in FIG. 2 along the B-B line. Asillustrated in FIG. 5, the lower flat surface of the heat pipe 6provided on the radiator 4 is arranged in contact with the flat portion42 a of the anti-air-leak sheet 42. The heat pipe 1 (the other end 1 bthereof) is arranged orthogonally to the heat dissipation fins 41.Accordingly, the radiator 4 is thermally connected to the heat pipe 1via the heat dissipation fins 41, and is thermally connected to the heatpipe 6 via the anti-air-leak sheet 42. Heat conducted from the heatgenerating component is transported through the heat pipe 6 anddissipated in a longitudinal direction of the anti-air-leak sheet 42 a.

The arrows in FIG. 5 indicate flows or streams of forced cooling airgenerated by a fan mechanism (not illustrated). Heat from the heat pipes1 and 6 is dissipated by the flows of air. As illustrated in FIG. 5, theboundary between the flat portion 42 a and the slope portion 42 b of theanti-air-leak sheet 42 is formed linearly along a longitudinal directionof the anti-air-leak sheet 42. Thus, this boundary defines a guidelineto specify a position where the heat pipe 6 is to be arranged in contactwith the anti-air-leak sheet 42. As described above, the heat pipe 6(the other end 6 b thereof) may be arranged between the anti-air-leaksheet 42 and the heat dissipation fins 41 and joined to the heatdissipation fins 41. This configuration is preferable in terms ofimprovement in cooling efficiency because the heat transferred throughthe heat pipe 6 can be directly conducted to the radiator 4.

Since the heat pipe 1 and the radiator 4 can be used in common in thecooling apparatus 10 and the cooling apparatus 10 a according to thefirst embodiment, the types of parts and components to be manufacturedand the number of parts and components to be managed can be reduced,resulting in cost reduction.

Further, the cooling apparatus 10 a, which has a simple configuration inwhich the bases 3 and 5 having the first heat receiving portion 3 a andthe second heat receiving portion 5 a, respectively, are provided fortwo heat generating components, and the heat pipe 6 as the second heatpipe for assisting the heat pipe 1 in heat transportation is attached ontop of the heat pipe 1, is capable of properly transporting the heatemitted from the second heating element and received by the heatreceiving portion 5 a to the radiator 4 (the other end 6 b thereof).

When the cooling apparatus 10 a is configured in this manner, itsthickness in the Z direction is increased by the provision of the heatpipe 6. However, when viewing the cooling apparatus 10 a in the X-Yplane, the surface area occupied by the heat pipe 6 in the X-Y plane isnot increased since the heat pipe 6 is placed on top of the heat pipe 1.

The base 5 is arranged to be located in an intermediate part of the heatpipe 1 in the cooling apparatus 10 a. Therefore, the surface areaoccupied by the cooling apparatus 10 a in the X-Y plane is increased bythe portions of the base 5 sticking out of the heat pipe 1 in the widthdirection. Nevertheless, the increase of the occupied area in the X-Yplane can be suppressed in comparison with the cooling apparatus of thecomparison example as illustrated in FIG. 18. This means that two heatgenerating components can be cooled with the cooling apparatus having areduced size in comparison with the cooling apparatus of the comparisonexample. Further, since the heat pipe 1 and the heat pipe 6 are formedinto a plate-like shape, the superposition of these heat pipes does notaffect significantly to the thickness. This is advantageous for exampleto reduce the thickness of the electronic apparatus.

Further, unlike the cooling apparatus of the comparison example (FIG.18), the cooling apparatus 10 a does not employ the configuration inwhich two heat pipes are inserted in the radiator. Therefore, theproblem that one of inserted two heat pipes hinders heat dissipation ofthe other heat pipe (obstructs the flow of air introduced into theradiator) can be avoided, whereby a desirable cooling effect can beobtained.

Modification Example

As described above, the cooling apparatus according to the invention isembodied not only in the cooling apparatus 10 having a basicconfiguration but also in various variations (modified embodiments)according to an amount of heat generated by a heat generating componentand relative layout of components. A modified embodiment of the coolingapparatus will be described, by way of example, in consideration of anamount of heat generated by a heat generating component and relativepositional relationship of components.

FIG. 6 is a perspective view illustrating a cooling apparatus 10 b thatis a modification example of the cooling apparatus 10 according to thefirst embodiment. FIG. 7 is a perspective view illustrating a coolingapparatus 10 d that is another modification example of the coolingapparatus 10 a according to the first embodiment.

The cooling apparatus 10 b illustrated in FIG. 6 is applicable to a heatgenerating component generating a greater amount of heat than a heatgenerating component to which the cooling apparatus 10 is applied. Thecooling apparatus 10 b differs from the cooling apparatus 10 in having aheat pipe 61 with a substantially equivalent length (path length) tothat of the heat pipe 1 in order to increase the amount of heattransported to the radiator 4.

The heat pipe 61 has substantially the same shape as the heat pipe 1,and has one end 61 a, the other end 61 b, and an intermediate portion 61c. The heat pipe 61 is arranged so as to be laid on the heat pipe 1 inthe X-Y plane from the one end 61 a to the other end 61 b, while the oneend and the other end of the heat pipe 61 are arranged to align with theone end and the other end of the heat pipe 1, respectively. In thismanner, the one end 61 a of the heat pipe 61 is enabled to receive heatfrom the heat receiving portion 3 a via the heat pipe 1, and to conductthe received heat to the other end 61 b via the intermediate portion 61c. The other end 61 b is arranged on the upper face of the radiator 4 inthe same manner as the other end 6 b of the heat pipe 6 (FIG. 2).

The cooling apparatus 10 b illustrated in FIG. 6 is capable of properlytransporting heat emitted from the heat generating component to theradiator 4 by means of the heat pipe 1 and the heat pipe 61. This meansthat, even if the amount of heat that the heat pipe 1 is able totransfer is not enough to transport the amount of heat generated by theheat generating component, the amount of heat that cannot be transportedby the heat pipe 1 can be covered by the heat pipe 61. Such increase ofamount of transportable heat can be achieved only by modifying thecooling apparatus 10 by arranging the heat pipe 61 on top of the heatpipe 1 and joining them. Thus, a cooling apparatus with an increasedamount of transportable heat can be obtained with a simple modification.

FIG. 7 illustrates a cooling apparatus 10 c that is a modificationexample of the cooling apparatus 10 a (FIG. 2), in which a heat pipe 61is superposed on the heat pipe 1 in the same manner as in the coolingapparatus 10 b illustrated in FIG. 6. In other words, one end of theheat pipe 6 illustrated in FIG. 2 is extended up to one end of the heatpipe 1.

The cooling apparatus 10 c having such configuration providessubstantially the same effects as the cooling apparatus 10 b.Specifically, the cooling apparatus 10 c is capable of properlytransporting heat emitted from the first heat generating component andreceived by the heat receiving portion 3 a to the radiator 4 by means ofnot only the heat pipe 1 but also the heat pipe 61. Therefore, thecooling apparatus 10 c is capable of properly cooling a heat generatingcomponent which generates a greater amount of heat than the first heatgenerating component to which the cooling apparatus 10 a is applied. Thecooling apparatus 10 c can be realized by such a simple modification ofthe cooling apparatus 10 a as to attach the heat pipe 61 thereto.Accordingly, even if the amount of heat generated by a heat generatingcomponent due to change of the heat generating component, the coolingapparatus 10 c capable of properly cooling the heat generating componentby a simple modification of the cooling apparatus 10 a.

Second Embodiment

A cooling apparatus according to a second embodiment will be described.The second embodiment has common features with the first embodiment.Therefore, the following description will be focused on differencesbetween the first and second embodiments, while like components will beassigned with like reference numerals and description thereof will beomitted.

FIG. 8 is a perspective view illustrating a configuration example of acooling apparatus 10 d according to the second embodiment. The coolingapparatus 10 d corresponds to a modification example of the coolingapparatus 10 according to the first embodiment. In the cooling apparatus10 a, the first and second heat generating components to be cooled arearranged on a straight line extended from the heat pipe 1 as viewed inplan (that is, the second heat generating component is arranged at aposition overlapping the intermediate portion 1 c of the heat pipe 1).Therefore, in this cooling apparatus 10 a, the configuration is employedin which the heat receiving portion 3 a as the first heat receivingportion and the heat receiving portion 5 a as the second heat receivingportion are both joined to the heat pipe 1. In contrast to this, thecooling apparatus 10 d according to the second embodiment has aconfiguration in which, although the second heat generating component isnot arranged on a path extended from the heat pipe 1, cooling of thesecond heat generating component is enabled with the use of the basicconfiguration (of the cooling apparatus 10 of FIG. 1).

Specifically, in the cooling apparatus 10 d illustrated in FIG. 8, thebase 3 having the heat receiving portion 3 a, the heat pipe 1, and theradiator 4 are the same as those of the cooling apparatus 10 (FIG. 1).However, the cooling apparatus 10 d differs from the cooling apparatus10 in the following respects.

(1) A second base 7 having a heat receiving portion 7 a for receivingheat from the second heat generating component is provided at a positionfurther away from the radiator 4 than the base 3 in the X-Y plane. Thebase 7 has threaded holes 7 b so that the base 7 is screw fastened tothe housing, a motherboard, or other component of the electronicapparatus.

(2) A heat pipe 62 is provided to transport heat from the heat receivingportion 7 a to the radiator 4. The heat pipe 62 is joined to the heatreceiving portion 7 a at its one end 7 a, and joined to the one end 1 aof the heat pipe 1 on the heat receiving portion 3 a. The heat pipe 62is extended so as to overlap with the heat pipe 1 from the one end 1 ato the other end 1 b of the heat pipe 1.

The following is a description of the heat pipe 62 in comparison withthe heat pipe 61 illustrated in FIG. 6. The configuration of the part ofthe heat pipe 62 overlapping with the heat pipe 1 is the same as that ofheat pipe 61. However, one end 62 a of the heat pipe 1 functions as anextension portion which extends further than the one end 1 a of the heatpipe 1, and this extension portion is joined to the heat receivingportion 7 a of the base 7.

Accordingly, the heat pipe 62 is able to transport heat conducted fromthe heat receiving portion 7 a onto the radiator 4 where the other end62 b is arranged. If the amount of heat transportable by the heat pipe62 allows, heat emitted from the heat receiving portion 3 a andconducted from the heat pipe 1 can also be transported to the radiator 4through the heat pipe 62.

The cooling apparatus 10 d illustrated in FIG. 8 has the base 7 and theheat pipe 62 added to the basic configuration of the cooling apparatus10, whereby the cooling apparatus 10 d is enable to also cool the secondheat generating component arranged near the first heat generatingcomponent corresponding to the heat receiving portion 3 a. Since a majorpart of the heat pipe 62 functioning as the heat conduction path isarranged to be laid on top of the heat pipe 1, the increase in thesurface area occupied by the cooling apparatus 10 d in the X-Y plane islimited to the increase of the area of extension portion (one end) 62 aof the heat pipe 62 and of the base 7. Thus, the cooling apparatus 10 dcan be obtained, which is able to cool the second heat generatingcomponent different from the first heat generating component with analmost minimum increase in the surface area.

FIG. 9 is a perspective view illustrating a configuration example ofanother cooling apparatus 10 e according to the second embodiment. Thecooling apparatus 10 e corresponds to a modification example of thecooling apparatus 10 a according to the first embodiment. Specifically,the cooling apparatus 10 e is a cooling apparatus in which the base 7and the heat pipe 62 illustrated in FIG. 8 are applied to the coolingapparatus 10 a. As illustrated in FIG. 9, the base 7 is provided forcooling a third heat generating component that is different from thefirst and second heat generating components the heat from which isreceived by the bases 3 and 5, and the heat pipe 62 is provided totransport the heat from the heat receiving portion 7 a to the radiator4. Particulars of the base 7 and heat pipe 62 are the same as those ofthe base 7 and heat pipe 62 illustrated in FIG. 8, and hence descriptionthereof will be omitted.

In addition to the advantageous effects provided by the coolingapparatuses 10 and 10 a, the cooling apparatuses 10 d and 10 eillustrated in FIGS. 8 and 9 are capable of realizing the cooling ofanother heat generating component (heat generating region) whilesuppressing the increase in size of the cooling apparatus in the X-Ydirection (in the planar direction), by such a simple method as addingthe base 7 and the heat pipe 62.

Third Embodiment

A cooling apparatus according to a third embodiment will be described.Since this third embodiment has common features with the first andsecond embodiments, the following description will be focused on theirdifferences. Like components will be assigned with the same referencenumerals and description thereof will be omitted.

FIGS. 10 and 11 illustrate a cooling apparatus 10 f according to a thirdembodiment which is a modification example of the cooling apparatus 10 aillustrated in FIG. 6. If the amount of heat transportable by the heatpipe 1 and the heat pipe 6 is not enough for the amount of heat receivedby the heat receiving portion 3 a, two heat pipes 61 are arranged on topof each other as illustrated in FIGS. 10 and 11. In this manner, byproviding a plurality of heat pipes 61 superposed on each other inaccordance with the desired amount of heat to be transported, the heatfrom the heat generating components can be properly transported to theradiator 4.

Particulars of the cooling apparatus 10 f illustrated in FIGS. 10 and 11will be described below. The cooling apparatus 10 f corresponds to amodification example of the cooling apparatus 10 b, in which the heatpipe 61 illustrated in FIG. 6 is laid in plurality (two in the figure)on top of the heat pipe 1, while being overlapped. A cooling apparatus10 f is another modification of the cooling apparatus 10 b illustratedin FIG. 6, in which one more heat pipe 61 is arranged on top of and incontact with the illustrated heat pipe 61. The upper flat surface of theheat pipe 61 to be superposed on the heat pipe 1 and the lower flatsurface of the heat pipe 61 additionally superposed on the heat pipe 61are joined in contact with each other and thermally connected to eachother. The joined two heat pipes 61 extend integrally along the samepath as the heat pipe 1 in the X-Y plane to reach the radiator 4.

As is obvious from the FIG. 11, one of the two heat pipe 61 integrallyextended to the radiator 4, namely the lower heat pipe 61 in the Z-axisdirection has its lower flat surface arranged in contact with the flatportion 42 a of the anti-air-leak sheet 42. The radiator 4 is thermallyconnected to the two overlapped and joined heat pipes 61 via theanti-air-leak sheet 42. The heat pipe 1 and the overlapped and joinedtwo heat pipes are separated upward and downward in the Z-axis directionbefore the radiator 4, and the overlapped and joined two heat pipesextend integrally onto the radiator 4.

Conductive heat from the heat generating component that is received bythe heat pipe 1 in the heat receiving portion 3 a is conducted to thelower heat pipe 61 via the lower flat surface of the lower heat pipe 61joined to the heat pipe 1. Further, since the lower flat surface of theupper heat pipe 61 arranged on the upper side in the Z-axis direction isjoined in contact with the upper flat surface of the lower heat pipe 61,the conductive heat conducted to the lower heat pipe 61 is conducted tothe upper heat pipe 61. Accordingly, the cooling apparatus 10 f of thismodification example is capable of increasing the amount of heattransported to the radiator 4, in comparison with the configuration ofthe cooling apparatus 10 b illustrated by way of example in FIG. 6.

This configuration of overlapping a plurality of heat pipes 61 is alsoapplicable to the heat pipe 62 illustrated by way of example in FIGS. 8and 9. Further, a modified embodiment can also be envisaged in which theheat pipe 61 is superposed on the heat pipe 62 to increase the amount oftransportable heat.

Fourth Embodiment

A cooling apparatus according to a fourth embodiment of the inventionwill be described. In the embodiments described in relation to FIGS. 6to 11, the radiator 4 and the heat pipe 1 are used as common coolingcomponents, and modified embodiments thereof are proposed by way ofexample in which additional heat pipes are provided to be superposed oneach other in accordance with an amount of heat generated by the heatgenerating components or positions where the heat generating componentsare arranged. In addition to these modifications, a modificationillustrated in FIG. 12 is also possible.

FIG. 12 is a perspective view illustrating by way of example a coolingapparatus according to the fourth embodiment. In the cooling apparatus10 g illustrated in FIG. 12, a heat pipe 63 one end of which is insertedinto a radiator 4 a different from the radiator 4 is superposed on andjoined to the heat pipe 61 of the cooling apparatus 10 b illustrated inFIG. 6. The radiator 4 a has the substantially same configuration asthat of the radiator 4 except that the heat pipe is inserted in mutuallydifferent directions. The heat pipe inserted into the radiator 4 a maybe one like the heat pipe 1, or may be one like the heat pipe 61. Aradiator different from the radiator 4 also can be used as the radiator4 a.

The upper flat surface of the heat pipe 61 and the lower flat surface ofthe heat pipe 63 are joined in contact with each other and thermallyconnected to each other. The heat pipe 61 and the heat pipe 63 areseparated leftward and rightward in the Y-axis direction at the positionwhere the heat pipe 61 and the heat pipe 1 are separated upward anddownward in the Z-axis direction. The end of the heat pipe 63 separatedfrom the heat pipe 61 is inserted into the radiator 4 a. Heat from theheat generating component conducted via the upper flat surface of theheat pipe 61 is transported to the radiator 4 a through the heat pipe63. The heat conducted from the heat generating component andtransported to the radiator 4 a is dissipated by means of the heatdissipation fins 41 a. A fan (not illustrated) is arranged in front ofthe radiator 4 a (on the near side from the radiator 4 a as viewed inFIG. 12) for supplying cooling air.

In the cooling apparatus 10 g, when the heat generating componentspossibly cannot be cooled enough by the configuration of the coolingapparatus 10 b (see FIG. 2), the configuration of the cooling apparatus10 g in which the radiator 4 a and the heat pipe 63 are provided can beemployed so that the heat is transported by the heat pipe 63 to theadditional radiator 4 a to be dissipated thereby.

In the cooling apparatus 10 g, the heat emitted from the heat generatingcomponent, received by the heat receiving portion 3 a and conductedthereto can be transported to corresponding one of the radiators 4 and 4a by the heat pipe 1, the heat pipe 61 and the heat pipe 63. Further,the configuration of the cooling apparatus 10 g is able realize acooling apparatus capable of properly cooling the heat generatingcomponents with a simple modification of adding the heat pipe 63 and theradiator 4 a to the cooling apparatus 10 a.

<<Electronic Apparatus>>

Electronic apparatus to which the cooling apparatuses according to thefirst to fourth embodiments of the invention are applicable will bedescribed with reference to FIGS. 13 to 17. FIG. 13 is an overallperspective view of electronic apparatus 30. FIGS. 14 to 16 are explodedviews of the electronic apparatus 30. FIG. 14 is an exploded view of theelectronic apparatus 30 as viewed from above, and FIG. 16 is an explodedview of the electronic apparatus as viewed from below. FIGS. 17A and 17Bare explanatory diagrams of a fan mechanism 39 and a cooling apparatusto be mounted on the electronic apparatus 30. The following descriptionwill be made in terms of a laptop PC as an example of the electronicapparatus 30.

As illustrated in FIGS. 13 and 14, the electronic apparatus 30 has alower housing 31, an upper housing 32, and a display 33. The lowerhousing 31 and the upper housing 32 define an internal space by beingjoined to each other. The display 33 is connected to the upper housing32 such that the display 33 is pivotable or rotatable around a pivotshaft 34 within a predetermined range of pivot angle with respect to theupper housing 32.

As illustrated in FIG. 13, the display 33 is opened in its substantiallycentral portion and provided with a display portion 33 a that is formedfor example of a liquid crystal display or organic EL(Electro-Luminescence) display. There is attached, on the upper surfaceof the lower housing 31, a keyboard 32 a including input means such askey input means or touch input means.

As illustrated in FIG. 14, there are accommodated, in the internal spacedefined by the lower housing 31 and upper housing 32 when joined to eachother, a CPU, a VGA, or an electronic circuit chip such as a LSI to becooled by a cooling apparatus, a wiring board (motherboard) 35 on whichelectric and electronic circuits and connectors are mounted, and acooling apparatus according to an embodiment of the invention. Thewiring board 35 may be a motherboard or the like on which a mainprocessor circuit of the electronic apparatus is mounted. The coolingapparatus used in the illustrated example is the cooling apparatus 10 aaccording to the second embodiment which has the heat pipe 1, theradiator 4, the bases 3 and 5, and the heat pipe 6.

The lower housing 31 is provided, for example, with a HDD device, abattery power source, and a fan mechanism 39 including a fan. There isformed, in a side face of the lower housing 31, a louver (air exhaust)31 a to face the air outlet of the fan mechanism 39. The louver 31 a isopened toward a lateral and obliquely downward direction of the lowerhousing 31. The louver (air exhaust) 31 a is formed for the purpose ofdischarging heat emitted from the heat generating component anddissipated by the radiator 4, out of the electronic apparatus 30.

The wiring board 35 has a plurality of threaded holes (through holes)35Z, and is fastened to the upper housing 32 with screws (notillustrated) using the threaded holes 35Z. The screw-fastened wiringboard 35 is fixed such that its element mounting surface faces the lowerhousing 31. In a state in which the element mounting surface faces thelower housing 31 as illustrated in FIG. 16, the heat generatingcomponents 36 a and 36 b project downward.

The cooling apparatus 10 a is accommodated within the electronicapparatus 30 while being interposed between the wiring board 35 and thelower housing 31 such that, unlike the state illustrated in FIG. 2, theside of the cooling apparatus, on which the heat pipe 6 and the heatpipe 1 are exposed, faces downward (that is, the cooling apparatus isturned upside down from the state illustrated in FIG. 2). Accordingly,when the cooling apparatus 10 a is accommodated in the electronicapparatus, there are arranged sequentially from the top to the bottom,the upper housing 32, the wiring board 35, the cooling apparatus 10 a,and the lower housing 31.

As illustrated in FIGS. 15 and 16, the cooling apparatus 10 a ispositioned such that the heat receiving portions 3 a and 5 a provided inthe bases 3 and 5 cover the heat generating components 36 a and 36 bmounted on the wiring board 35. The wiring board 35 has through holespassing through the wiring board 35 at the positions corresponding tothe through holes provided in the projections of the support members 11a to 11 d when the cooling apparatus 10 a is positioned in this manner.Attachment parts having threaded holes 35 a to 35 d are arranged on thesurface of the wiring board 35 which defines the rear face of the wiringboard 35 on which the cooling apparatus 10 a is arranged (for example,the upper surface of the wiring board 35 in FIG. 15). These threadedholes 35 a to 35 d are provided in the respective attachment parts atpositions corresponding to the through holes provided in the wiringboard 35.

When attaching the cooling apparatus 10 a to the wiring board 35, thecooling apparatus 10 a and the attachment parts are firstly arranged onthe wiring board 35 such that the through holes formed in theprojections of the support members 11 a to 11 d of the cooling apparatus10 a, the through holes in the wiring board 35, and the threaded holesof the attachment parts are all aligned with each other. Screws areinserted in the through holes formed in the projections of the supportmembers 11 a to 11 d of the cooling apparatus 10 a, and these screws arefastened to the threaded holes of the attachment parts via the throughholes in the wiring board 35. According to such an attachmentconfiguration, the relative position between the wiring board 35 and thecooling apparatus 10 a (particularly, the opposing position between theheat generating components 36 a, 36 b and the heat receiving portions 3a, 5 a) will not vary even if vibration occurs in the components of theelectronic apparatus 30 due to carrying of the electronic apparatus.Therefore, the cooling apparatus 10 a is capable of ensuring stable heatexhaust capacity for the heat generating components.

When the electronic apparatus 30 is powered on and an OS (OperatingSystem) stored in a HDD device or the like is started, heat from theheat generating components 36 a, 36 b is conducted to the heat pipes 1and 6 via the heat receiving portions 3 a and 5 a which are arranged toface and cover the heat generating components 36 a, 36 b. The heat fromthe heat generating component conducted from the heat pipes 1 and 6 istransported to the radiator 4 through these heat pipes 1 and 6 servingas heat conduction paths. The radiator 4 of the cooling apparatus 10 ais accommodated in a space between the fan mechanism 39 and the louver(air exhaust) 31 a provided in the lower housing 31. Forced cooling airintroduced through the opening 41 c of the radiator 4 facing the airoutlet of the fan mechanism 39 passes through between the heatdissipation fins 41 of the radiator 4 and discharged out of theelectronic apparatus 30 via the louver (air exhaust) 31 a.

FIGS. 17A and 17B illustrate a positional relationship among the coolingapparatus 10 a fixed to the electronic apparatus 30, the fan mechanism39 and the louver (air exhaust) 31 a. The opening 41 c of the radiator 4accommodated in the lower housing 31 faces the air outlet of the fanmechanism 39. Airflow generated by the fan mechanism 39 and introducedthrough the opening 41 c passes through between the heat dissipationfins while catching the conductive heat dissipated via the heatdissipation fins 41, and is discharged out of the electronic apparatus30 through the louver (air exhaust) 31 a. Accordingly, the conductiveheat from the heat generating components which has been conducted andtransported through the heat pipe 1 and the heat pipe 6 is dischargedout of the electronic apparatus 30 through the louver (air exhaust) 31 atogether with the airflow generated by the fan mechanism 39.

In the C-C cross-sectional view of FIG. 17B, the arrows indicatedirections in which the airflow generated by the fan mechanism 39 passesthrough. As is seen from the C-C cross-sectional view of FIG. 17B, inthe state in which the cooling apparatus 10 a is held and fixed in theelectronic apparatus 30, a space is formed between the heat pipe 6 incontact with the anti-air-leak sheet 42 of the radiator 4 and the lowerinner surface of the lower housing 31. This gap structure allows part ofthe airflow generated by the fan mechanism 39 to pass through the spacebetween the flat face of the heat pipe 6 and the lower inner surface ofthe lower housing 31 to be discharged out of the electronic apparatus 30through the louver (air exhaust) 31 a.

Thus, the cooling apparatus according to this embodiment is enabled, bybeing mounted on the electronic apparatus 30, to assume a heat exhaustconfiguration utilizing the housing structure of the electronicapparatus 30. This improves the heat diffusion capacity of the heat pipe6 fastened to the anti-air-leak sheet 42 of the radiator 4. Theconfigurations of the aforementioned embodiments can be combined asrequired without departing from the scope of the invention.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. A cooling apparatus for cooling a heating element accommodated in anelectronic apparatus, the cooling apparatus comprising: a heat receivingportion to receive heat from the heating element; a radiator; a firstheat pipe having one end portion to receive heat from the heat receivingportion and anther end portion inserted in the radiator; and at leastone second heat pipe to receive the heat from the heat receiving portionvia the first heat pipe, the second heat pipe including one end portionarranged on the first pipe and another end portion arranged around theradiator, wherein the second heat pipe overlaps with a region of thefirst heat pipe extending from the heat receiving portion to theradiator in a plan view of the cooling apparatus.
 2. The coolingapparatus according to claim 1, further comprising a second heatreceiving portion different from the heat receiving portion, whereinheat from the second heat receiving portion is received at the one endportion of the first heat pipe.
 3. The cooling apparatus according toclaim 1, further comprising a second heat receiving portion differentfrom the heat receiving portion, wherein heat from the second heatreceiving portion is received at the one end portion of the first heatpipe, and wherein the second heat pipe overlaps with a region of thefirst heat pipe extending from the second heat receiving portion to theradiator in a plan view of the cooling apparatus.
 4. The coolingapparatus according to claim 1, further comprising a second heatreceiving portion different from the heat receiving portion, wherein thesecond heat pipe includes one end of a radiator side and another end ofa heat receiving portion side, and wherein the anther end receives heatfrom the second heat receiving portion via the first heat pipe.
 5. Thecooling apparatus according to claim 4, further comprising a third heatreceiving portion arranged between the heat receiving portion and theradiator, wherein the first heat pipe receives heat from the third heatreceiving portion, and wherein the second heat pipe receives the heatfrom the third heat receiving portion via the first heat pipe.
 6. Thecooling apparatus according to claim 1, wherein two or more second heatpipes overlapping each other are arranged on the first heat pipe.
 7. Thecooling apparatus according to claim 1, further comprising: a secondradiator different from the radiator; and a third heat pipe to receivethe heat from the heat receiving portion via the first heat pipe and thesecond heat pipe, wherein the third heat pipe includes one end portionoverlapping the second heat pipe and another end portion inserted in thesecond radiator.
 8. The cooling apparatus according to claim 1, whereinthe first heat pipe is formed in a flat strip shape.
 9. The coolingapparatus according to claim 1, wherein the second heat pipe is formedin a flat strip shape.
 10. An electronic apparatus, comprising: ahousing; a heating element accommodating the housing; and a coolingapparatus to cool the heating element, the cooling apparatus including:a heat receiving portion to receive heat from the heating element; aradiator; a first heat pipe having one end portion to receive heat fromthe heat receiving portion and anther end portion inserted in theradiator; at least one second heat pipe to receive the heat from theheat receiving portion via the first heat pipe, the second heat pipeincluding one end portion arranged on the first pipe and another endportion arranged around the radiator, wherein the second heat pipeoverlaps with a region of the first heat pipe extending from the heatreceiving portion to the radiator in a plan view of the coolingapparatus; and a fan to generate airflow which flows inside and aroundthe radiator, and flows out from an air exhaust formed in the housing.